Embossing cellulosic absorbent sheet products to alter their mechanical or tactile characteristics is well known. There is shown in U.S. Pat. No. 1,808,536 to Fisk a method and apparatus for embossing paper tissue and towels using an embossing roll with a wave-like pattern. The pattern on the roll has a relief height of 0.075 or more above the general surface of the roll (col. 2, lines 69–75). The method is reported to be particularly suitable for wet creped products, prior to the web contacting drier rolls.
There is shown in U.S. Pat. No. Des. 186,259 to Howell a puffed textile fabric with a wave-like design. So also, U.S. Pat. No. 728,828 to Arkell shows a bi-directional wave pattern imposed on a paper structure.
U.S. Pat. No. 3,672,950 of Murphy et al. is directed to adhesively laminated creped products wherein the plies are bonded in superposed relation by an adhesive disposed between the webs (col. 2, lines 15–25). The adhesive may be applied in a wave-like pattern in the machine direction (FIGS. 1,4), while the webs may be embossed with a great number of pin-like embossments. The embossments extend from the body of the web for a predetermined distance as required to keep the two webs suitably spaced, the two webs being superposed with the protuberances of each web facing the other web (col. 4, lines 29–37; col. 6, line 74–col. 7, line 1).
In U.S. Pat. No. 4,339,088 to Niedermeyer there is described an embossing method to avoid nesting in convolutedly wound rolls wherein the repeat length is at least as great as the circumference of the roll. In Example I, a sine wave pattern of embossment nodes is laid out in the machine direction (col. 4, lines 5–35).
U.S. Pat. No. 5,861,081 of Bredendick describes a single ply-paper towel with a plurality of infundibulate bosses formed therethrough. The towel has areas of light bosses and heavy boss perforations which form islands of heavy boss perforations surrounded by intersecting bands of light bosses (col. 3, lines 33–38).
Air-laid absorbent sheet products are likewise well-known. U.S. Pat. No. 4,437,917 to Tao et al. describes a method of increasing the caliper and bulk of air-laid dry fibrous webs. The method generally includes measuring the caliper downstream of the bond curing drier and adjusting drier conditions on the basis of the caliper measurements.
U.S. Pat. No. 4,482,308 to Johnson teaches an apparatus for depositing dry fibers on a foraminous support including offset suction and air deflecting means for imparting a horizontal velocity component to the fibers in the direction of the moving wire. The patent reports more uniform distribution of fibers in the product.
U.S. Pat. No. 4,476,078 to Tao reports that air-laid webs are conventionally embossed either before or after the binder is applied and cured; each method having its advantages and drawbacks. Pre-embossing is reported to reduce line speed, while post-embossing lacks good embossing definition (col. 1, line 58–col. 2, line 13).
U.S. Pat. No. 4,612,231 of Bouchette et al. describes a patterned air-laid fibrous web of enhanced absorbency. According to the '231 patent, absorption rates are increased when at least about 40 percent of the imprinted area of the web is compressed (col. 2, lines 23–28).
Another method of increasing the absorbency of air-laid webs is disclosed in U.S. Pat. No. 5,128,082 to Makoui. The '082 patent describes making an absorbent structure by dry laying a fibrous web having incorporated therein a superabsorbent material such as poly(acrylic acid) or a salt thereof and apply a latex coating to at least one surface of the web.
Wave-like patterns have been employed to control fluid distribution in absorbent structures. U.S. Pat. Re 29,789 to Kolbach discloses a diaper with various emboss patterns. There is disclosed, for example, an emboss roll with circumferential wave bosses (46, FIG. 1) extending in the cross direction of a production line. The diapers have compressed channels 72 with a wavy line profile which function to direct fluid in the longitudinal direction. Col. 7, lines 60–63; column 8, lines 40–44.
U.S. Pat. No. 2,788,003 to Morin discloses a multi-layer diaper embossed with a wave-like pattern. The wave-like pattern is formed by embossing strips of the absorbent layer 17 against the facing sheet with a hot embossing tool. Column 3, lines 34–43. The embossed strips operate to convey fluid in the direction of the emboss lines. Column 4, lines 29–51.